(57) An internal exhaust fan (56) propels internal solvent-laden air across a burner (66)
where it combusts, causing a heat rise. Heated, combusted air is routed to a recirculating
supply air fan (50) which provides pressurized heated air for air bars (28a-28n, 30a-30n)
for drying a web. Heated air in excess of that required to dry the web is vented externally
and helps to maintain desired solvent concentration levels. Variable parameters such
as fan speed, burner temperatures, air box pressures, exhaust air rate, solvent concentration,
supply air flow, supply air temperature and damper position are monitored, and the
components are actuated to effect a high level of clean up efficiency. The control
system provides for the coordinated control of the exhaust fan speed, damper positions,
and burner firing. The control system utilizes a computer in real time processing
to monitor and control the electrical and electromechanical components.
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